feat: i18n user interface (#40306)

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>

client/src/client-only-routes/ShowSettings.test.js

@@ -14,7 +14,7 @@ describe('<ShowSettings />', () => {
     expect(result.type.toString()).toBe('Symbol(react.fragment)');
     // Renders Helmet component rather than Loader
     expect(result.props.children[0].props.title).toEqual(
-      'Settings | freeCodeCamp.org'
+      'buttons.settings | freeCodeCamp.org'
     );
   });